Android ranging does not work

BLE Beacons
1

beaconManager.setMonitoringListener is working but beaconManager.setRangingListener not working.
Can you help me?
Thanks
It was coded as follows:

Region region;
BeaconManager beaconManager;

@Override
protected void onCreate(Bundle savedInstanceState) {
  beaconManager = new BeaconManager(this);
  region = new Region("ranged region", UUID.fromString("B9407F30-F5F8-466E-AFF9-25556B57FE6D"), null, null);
  
  beaconManager.setRangingListener(new BeaconManager.RangingListener() {
    @Override
    public void onBeaconsDiscovered(Region region, List<Beacon> list) {
      Log.d("myLog", "onBeaconsDiscovered  " + "onBeaconsDiscovered !!'");
      if (!list.isEmpty()) {
        Beacon nearestBeacon = list.get(0);
      }
    }
  });
  
}

@Override
protected void onStart() {
  super.onStart();
  
  SystemRequirementsChecker.checkWithDefaultDialogs(this);
  
  beaconManager.connect(new BeaconManager.ServiceReadyCallback() {
    @Override
    public void onServiceReady() {
      try {
        beaconManager.startRanging(region);
      } catch (Exception e) {
        Log.d("myLog", "Errore scansione Beacon : " + e.getMessage());
      }
      
    }
  });
}

@Override
protected void onStop() {
  beaconManager.stopRanging(region);
  
  super.onStop();
}
2

What does “not working” mean? Not getting called at all? Gets called with an empty array?

3

Same problem, if i print a log with the list size it shows 0.